<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>404 - 没有题目啦！</title>
    <style>
        body, html {
            height: 100%;
            margin: 0;
            font-family: Arial, sans-serif;
        }
        .bg {
            /* 使用一个渐变背景 */
            background: linear-gradient(120deg, #a1c4fd, #c2e9fb);
            height: 100%;
            display: flex;
            justify-content: center;
            align-items: center;
            text-align: center;
            color: #333;
        }
        .content {
            max-width: 600px;
        }
        h1 {
            font-size: 3rem;
            margin: 0;
            color: #56ccf2;
        }
        p {
            font-size: 1.2rem;
            color: #777;
        }
        a {
            display: inline-block;
            background-color: #56ccf2;
            color: white;
            padding: 10px 20px;
            text-decoration: none;
            border-radius: 5px;
            margin-top: 20px;
            transition: background-color 0.3s ease;
        }
        a:hover {
            background-color: #2d98da;
        }
    </style>
</head>
<body>
    <div class="bg">
        <div class="content">
            <h1>404</h1>
            <p>没有题目啦！</p>
            <a href="/">返回首页</a>
        </div>
    </div>
</body>
</html>